CONTRIBUTORS: add myself

GiedriusS · Giedrius Statkevičius · commit 1caf62960c74 · 2018-11-27T14:56:48.000+02:00
diff --git a/CONTRIBUTORS b/CONTRIBUTORS
@@ -31,3 +31,4 @@ Rhommel Lamas (rhoml)
 Jose Luis Ledesma (sp-joseluis-ledesma)
 Matthias Baur (baurmatt)
 Gavin Williams (fatmcgav)
+Giedrius Statkevičius (GiedriusS)
